Cooling system



June 15, 1937. H. H. MARSHALL 2,033,611

000mm SYSTEM Filed Dec. 5, 1951 2 Sheets-Sheet l June 15, 1937. H H,MARSHALL 2,083,611

COOLING SYSTEM Filed Dec. 5, 1931 2 Sheets-Sheet 2 k I Z; 5

Patented June 15, 1937 UNITED STATES.

PATENT OFFICE COOLING SYSTEM ware Application. December 5, 1931, SerialNo. 579,159

5 Claims.

This invention relates to an improved method and apparatus for theremoval of heat at one temperature and the dissipation of the removedheat at some lower temperature.

5 The general object of the invention is to provide for the absorptionof heat at a desired temperature, the absorbing medium being adapted tocarry the heat to ,a point at which it is then dissipated to theatmosphere, or other- 10 wise, at a lower temperature.

Another object of the invention is to provide means for controlling,within desired limits, the higher temperature at which this heat isabsorbed, regardless of variations in the lower 15 temperature at whichthe heat is subsequently dissipated. j

In carrying out these objects, applicant employs a suitable medium. suchas dichloromethane or dichloroethylene, or other refrigerants 2 havingrelated characteristics. This refrigerant is circulated about anapparatus to be cooled, and since its inherent characteristics enable itto be converted from liquid to vapor state, at comparatively slightpressures, exceedingly 25 rapid and eflicient heat exchange will takeplace in carrying on cooling operations, even at comparatively lowtemperatures. In the heat exchange step, the refrigerant, in absorbingheat, will be converted into, a vapor. In the usual 30 refrigerationcycle, this vapor would then be compressed, and after the compressionoperation, would be subjected to condenser action in which the vaporwould be reconverted into liquid form. Applicant, however, has conceived35 that such compression is unnecessary in carrying on controlledcooling operations, where the temperature of the apparatus or medium tobe cooled need not be lower than the temperature of the atmosphere orany desired medium 40 adapted to be employed in reconverting arefrigerant from vaporous to liquid form. In practical application,-therefore, a refrigerant such as dichloromethane could be circulatedabout a cylinder, of a gas engine, for example, remove 45 heattherefrom, and in consequence, be converted, by evaporation. to a vapor.The vapor would then proceed to a condenser, cooled by water, or by air,the cooling step reconverting the refrigerant to liquid form. The liquidmay 50 then be returned to the cylinder and the operation repeated.

A feature of the invention resides in the provision of a condenseremployed. for converting refrigerant from vaporous to liquid state and55 means for governing the condenser action so that the rate ofconversion of refrigerant to liquid state may be accomplished at apredetermined rate.

Another feature resides in the control of the temperature of an objectto be cooled by means of a condenser adapted to convert refrigerant usedin the cooling operation from vaporous to liquid form, the condenserbeing adapted to regulate the pressure at which said refrigerant isconverted from liquid to vaporous form.

Still another feature resides in the provision of means in combinationwith. a condenser whereby the rate of evaporation of a refrigerant maybe controlled and the condensation of said refrigerant also controlled.

Another feature resides in using a refrigerant as a heat absorptionmedium in a closed cooling circuit, the circuit adapted to be sealed,and the cooling operation adapted to be efficiently carried on eventhough the amount of refrigerant remains constant under all operatingconditions.

Other features making for efliclency and economy in operation andaccomplishingdesired methods of control by various means, includingregulation of condenser cooling, adjustment of condenser surface.variation 'of evaporation and condenser pressures. and furtheradvantages in structure and design in apparatus suitable for carryingout the invention, will be more apparent from the following descriptionof the invention, to be read in connection with the accompanyingdrawings, showing illustrative forms of application, in which:

Fig. 1 is a diagrammatic view of a simple application of my invention,

Fig. 2 shows another form of my cooling arrangement illustrating adifferent method of control,

Figs. 3, 4, and 5 illustrate modified forms of applying the invention inthe accomplishment of controlled cooling operations,

Fig. 6 shows the cooling system applied internal combustion engine, and

Fig. 7 is a section of part of the cooling system of Fig. 6.

Considering the drawings, more particularly Fig. 1, numeral 1 designatesan area containing a source of heat. In practice, it may be a device,either electrical of mechanical, or a container in which a chemicalprocess takes place, giving of! heat at a constant or varying rate. AreaI is surrounded by a jacket 2, containing a heat transfer medium 3,shown in liquid form. The jacket is connected by passage l to condenser5. The condenser is formed. preferably, of a number of tubes to an 6,having finned surface thereon to facilitate heat transfer. The tubes areconnected at their opposite ends to headers l, suitably provided withsupply and discharge lines, respectively designated B and 9. Valve H) inthe supply line operates responsive to control device II. This devicemay operate responsive to changes in temperature or in pressure withinjacket 2, and regulate the entrance of condenser cooling liquid to line8. In practice, the arrangement of Fig. 1 will preferably operate witha. refrigerant within the jacket, such as dichloromethane. Others,however, having similar or related characteristics, such asdichloroethylene, may also be used. Upon the generation of heat withinarea i, some of the refrigerant liquid will evaporate, thus causing atransfer of heat from the chamber to the liquid. The vapor will thenrise and enter condenser 5 through whose tubes 6 comparatively coldwater will be circulating. The vapor will thereupon be condensed anddrop back within the jacket. The control device ll responds, as, forexample, if it is a thermostatic device, to changes in .temperaturewithin the jacket. Thus, when more heat is generated in area I, it willcause more water to pass through valve l0 and enter condenser 5,whereas, whenless heat is given off, valve ID will correspondingly becontrolled to admit less water within the condenser. As a result, thecondensing action is regulated responsive to variations in heat loadproduced within area I. Area I will, therefore, be maintainedsubstantially at constant temperature. The device ll, instead of beingresponsive to changes in temperature, may react similarly to changes inpressure. The result, however, will be the same.

Dichloromethane is preferred as a refrigerant because it is peculiarlyadapted to achieve applicants desired results. Its stability underalmost all conditions within practical limits, its nontoxic character,the fact that it is non-inflammable, and that it will not corrode orcoat surfaces, make it ideal for use as a cooling medium in anarrangement such as illustrated in simple form, by Fig. 1. Of particularimportance, however, is the fact that dichloromethane is a liquid atatmospheric pressure at normal temperatures, under F., and its escapefrom the system is of no moment, because it will resume the liquid form.Since it is non-inflammable, non-explosive and non-toxic, it will do noharm nor create any unsatisfactory conditions. Also, its operatingcharacteristics require but comparatively slight pressure for itsevaporation even at temperatures of several hundred degrees Farenheit,whereas, such refrigerants as ammonia or propane, under similarconditions, would require tremendous structures capable of withstandingpressures up to and exceeding one thousand pounds per square inch.Besides, such other refrigerants are both unstable, as well asdangerous.

Fig. 2 illustrates a more comprehensive method of applying the coolingarrangement shown in Fig. 1. Area I has a similar jacket 2 containing aheat transfer medium such as dichloromethane 3. The condenser 5 in thiscase is air cooled, instead of water cooled. Any suitable means, such asa fan, not shown, or natural circulation of air about the condenser maybe relied upon to bring about the desired condenser cooling effect.Valve I! at the discharge end of the condenser permits refrigerant inliquid form to leave the condenser, in controlled amounts. However, ifvalve [2 remains closed, liquid will be stored within the condenser and,in effect, reduce the effective conated under similar conditions.

denser area. The operation of valve [2 is under control of device l3,which responds to changes either in temperature or pressure within thejacket. Reservoir I 4 receives liquid passing through valve (2 which maythen fiow through line i 5 and enter the jacket under control of valvel6. Valve IE is under control of device I! which may respond to changesin temperature (or pressure) within jacket 2. It is evident that'insteadof having two devices [3 and l! for the control respectively of valvesl2 and IE, only one device may be used, since both valves are similarlyactu- Two devices are shown because, in practice, it may be desired toactuate one valve responsive to temperature changes, whereas the othervalve could more efficiently be operated responsive to pressure changes.The operation, as in Fig. 1, comprises the evaporation of refrigerant 3,due to the production of heat within the area I. The vapor then passesto the condenser 5 and is reconverted into a liquid by an air coolingaction. The valve l2, responsive to its control device l3, will allowthe condensate to pass through in the event the heat load calls forfurther cooling. However, if the temperature conditions within area I donot require lowering of temperature, valve I! will remain shut and allowthe liquid to accumulate within the condenser tubes, thus cutting downthe effective condenser area and correspondingly reducing the condensingaction. It may be noted that as the liquid refrigerant accumulates inthe condenser, the pressure on the evaporating liquid will be increased,with a consequent reduction in evaporation. As further cooling isrequired, due to increase in load, valve [2 will open and valve IE willalso open, thus permitting liquid to flow from the condenser back to thejacket. Reservoir i 4 stores up excess liquid which is admitted by,valveI8, so that the liquid level within the jacket may be maintainedsubstantially at a desired point. Valves i2 and I6, therefore, serverespectively to maintain the temperature of area I substantiallyconstant by regulating the condenser action and the level of liquidwithin the jacket. Not only is the control of level in the jacketimportant from the standpoint of maintaining substantially constanttemperatures. within the area but the maintenance of the jacket walls inwetted condition is highly desirable in effecting maximum heat 7transfer.

Figs. 3, 4 and 5 illustrate modified forms of applying the invention,showing various methods of control. In Fig. 3, damper 20 operatesresponsive to control i9, similarly situated as are controls i3 and ITin Fig. 2. The damper motor l8 will, therefore, regulate the position ofdamper 20 within the passage connecting jacket 2 and condenser 5. Thisdamper, in effect, regulates the pressure on the liquid in the jacketand thus controls therate of evaporation. Pump 2| can draw liquidrefrigerant through passage 22 from the condenser 5. The pump dischargesthe liquid through passage 24, leading to spray deck 25 situated at theupper or discharge end of the jacket. The pump operates continuously anda flood of spray, therefore, constantly serves the jacket and retainsthe walls wetted at all times. The rate of evaporation, as alreadynoted, will be controlled by responsive to the position of float valve26 within reservoir 21. The reservoir serves to accumulate condensate,and when it reaches a certain level, the float .valve will serve toactuate an electrical switch and close a related circuit for operatingthe pump. A switch of any suitable design may be'used whose contacts maybe closed when the float reaches one position, and broken when the floatreaches another position. The. use of this control assures the main-'tenance of a substantially constant level of liquid within the jacket.Damper 20, as in Fig. 3, is controlled by motor IS, in turn operativeresponsive to changes in conditions aifecting de- 'vice l9, and hencecontrols the rate of evaporation by governing the pressure on the liquidin the jacket. Check valve 28 is arranged to prevent the liquid flowingback to the pump from the jacket, whenever the-pump is inoperative.

Fig. 5 represents another variation in the method of control. Valve 29is here under control of device 30 which responds, as in Figs. 3 and 4,either to changes in pressure or temperature within the jacket. When thetemperature rises, as in the case of. an increasing load, device 30 willcause valve 29 to open and the pump 2| will thereupon supply liquid fromreservoir 21 to the jacket. The pump is of the centrifugal type andhence may operate continuously, supplying liquid as requirements demandwhenever the regulating device operates valve 29. This arrangementobviates the necessity for a controlled motor circuit, as, for example,shown in Fig. 4. The control of temperature w thin area i is, as inFigs. 3-and 4, carried on by damper which regulates the pressure on theliquid within the jacket and hence the rate of evaporation.

In Figs. 6 and 7, applicant illustrates a practical embodiment of hisinvention, in connection with the cooling of an automobile or internalcombustion engine. In effect, the internal combustion engine hereillustrated takes the place oi area I shown in the other figures. Theengine may be of conventional design, and, per se. forms no part of theinvention. The cooling system may include the usual jackets about thecylinders and various other elements such as connections, pump.reservoir, and radiator. The radiator 3| takes the place of thecondenser 5 shown in the other figures. A suitable reservoir orreceiving tank 32 is located in the bottom of the radiator. A series oflouvres 33 are suitably positioned in front of the radiatnr. so thatonrushing air responsive to the forward motion of the motor or vehiclein which the motor is located will pass through the tubes of theradiator in varying amount depending upon the position of the louvres. Afan 34 provided in the usual manner and operative from one,-of theshafts of the motor may be used to draw air through the "radiator and incontact with the tubes thereof, so that the cooling operation may becarried on even though the engine remains stationary. The control motor35, analogous in construction to the damper motor I8 of Figs. 3, 4 and5, operative responsive to control device 36, shown on Fig. 6, regulatesthe position of louvres 33. Thus, as the engine requires more coolingeffect, control device 36 will cause the damper louvre control motor 35to open louvres 33 wider, so that more air will pass over the tubes ofthe radiator, thereby producing greater cooling effect. Of course,whenever the engine speeds up, fan 34 and pump 31' are also speeded up.However, unless the heat were not dissipated fast enough, the louvres 33would remain unafiected. However, if, as, for example, under a load, theengine did not speed up, but the amount of heat to be dissipatedincreased, the control 35 would be actuated and cause louvres 33 tofunction so that more air would pass the radiator tubes. Thus, by controlling the condenser action in the radiator, the temperature of theengine would be maintained substantially constant. It should be observed that not only is the method of control peculiarly adapted tomaintain desired constant temperature conditions, but the use ofrefrigerants such as dichloromethane has many other salutary advantages.The refrigerant may be sealed in, so that in amount it always remainsthe same and yet its cooling effect can be varied, depending uponchanges in rate of evaporation, controlled through regulation of thecondenser action. The danger of freezing does not exist. Furthermore,but a small quantity of refrigerant is required, compared to the amountof water, for example, needed .to accomplish similar results; but themore important factor is that the condensing surface required with thisrefrigerant is much smaller than that of the conventional radiator ofequal capacity. Also, the use of refrigerant such as dichloromethanewould not rust the interior of the jackets, nor would ever require-replacement or inspection during the life of the engine.

While the invention is shown applied to an internal combustion engine,it is obvious that a cooling arrangement of similar design may beadapted in countless systems wherein the dissipation of heat and themaintenance of substantially constant temperatures is desired. Themethods of control shown in the drawings are not to be construed aslimiting, but merely as illustrative of the ways in which the inventionmay be applied.

It is intended that the foregoing description and the accompanyingdrawings be regarded as illustrative only and not in a limiting sense,ap-

plicant limiting himself only as indicated in the accompanying claims.

. What I claim is:

1. A method of maintaining constant the temperature of an objectcontaining a source of heat consisting in surrounding said object with aliquid adapted to evaporate, and controlling the rate of evaporation bycontinually passing a condensing fluid in heat exchange relation withthe vapors resulting from the evaporation of said liquid andquantitatively regulating the flow of condensing fluid.

2. A method of maintaining constant the temperature of an objectcontaining a source of heat consisting in surrounding said object with aliquid adapted to evaporate, whereby said liquid is vaporized,condensing the resultant vapors, at substantially the same pressure asthe pressure with which these vapors were formed, by passing a coolingmedium in heat exchange relation with the vapors at all times, returningthe condensate for re-evaporation, and quantitatively controlling theamount of cooling medium passed in heat exchange relation with saidvapors by the temperature of said liquid.

3. A method of regulating the temperature of an object to be cooledconsisting in evaporating a liquid in contact with the object,condensing the resultant vapors, at substantially the same pressure asthe pressure at which these vapors were formed, by causing a change inthe sensible heat only of a cooling medium by passing the same in heatexchange relation with the vapors, returning the condensed liquid sothat it may again contact with said object, and regulating the flow ofcooling medium by variations in the amount of heat tobe dissipated.

4. A method of regulating the temperature of an object to be cooledconsisting in wetting the surface of said object with a volatile fluidwhereby the fluid is evaporated, condensing the resultant vapors, atsubstantially the same pressure as the pressure at which these vaporswere formed, by continuously, and at all times, circulating a cooledmedium in heat exchange relation with the vapors, and controlling therate of condensation by regulating quantitatively the flow of coolingmedium by the temperature of said fluid.

5. A method of cooling an object subjected to varying heat loadsconsisting in wetting the surface of said object with a volatile fluidwhereby the fluid is evaporated, condensing the resultant vapors, atsubstantially the same pressure as the pressure at which the vapors wereformed, by continuously causing a change in the sensible heat of acooling medium by circulating the same in heat exchange relation withthe vapors, and controlling the rate of condensation by regulatingquantitatively the flow of cooling medium.

HENRY Hi MARSHALL.

